Rayleigh surface acoustic wave sensor for ppb-level nitric oxide gas sensing

•The RSAW sensor with Cu2+/PANI/SnO2 nanocomposite film to ppb-level NO gas were investigated.•The sensor with this film exhibited good sensitivity and the detection limit was 5ppb NO gas at room temperature.•This sensitive layer showed high selectivity to NO gas since any interference from NO2, CO2 and O2 was negligible.•This work shows the potential to apply the Cu2+/PANI/SnO2 RSAW sensor to biosensors for extremely low NO concentrations. A copper ion-doped polyaniline/tin oxide nanocomposited film, Cu2+/PANI/SnO2, was investigated on a Rayleigh surface acoustic wave device for nitric oxide (NO) gas sensing at room temperature. The surface morphology, chemical structures and the electric properties were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Hall Effect measurement, respectively. Copper ion-doped sensing film, Cu2+/PANI/SnO2, exhibited high NO gas sensitivity, repeatability and long-term stability. Moreover, it showed an estimated detection limit of 5ppb. The sensor exhibited distinctive selectivity towards NO gas with no significant response to NO2, CO2 and O2 gases.